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Study on the Elastic-Plastic Correlation of Low-Cycle Fatigue for Variable Asymmetric Loadings
Junhong Zhang1,2, Weidong Li1, Huwei Dai1
1State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China.
Materials (Basel, Switzerland)
|June 3, 2020
Summary
A new strain ratio-based model improves low cycle fatigue (LCF) life predictions for asymmetric loading. This model accounts for ratcheting strain, offering better accuracy than traditional mean stress methods for various materials.
Area of Science:
- Materials Science
- Mechanical Engineering
- Fatigue Analysis
Background:
- Classical low cycle fatigue (LCF) models struggle with asymmetric loading due to mean stress effects.
- Existing models show limitations in accuracy and applicability for varying materials and conditions.
Purpose of the Study:
- To analyze the influence of strain ratio (R) on LCF life.
- To develop and present a novel strain ratio-based model for asymmetric loading scenarios.
Main Methods:
- Introduced two correction factors relating strain ratio to fatigue strength and ductility coefficients.
- Validated the model using high-pressure tubing steel, aluminum alloy, epoxy resin, and magnesium alloy under diverse strain ratios.
Main Results:
- The proposed strain ratio-based model demonstrates superior life prediction accuracy compared to widely used LCF models.
- The model effectively addresses asymmetric loading cases for multiple materials.
Conclusions:
- The strain ratio-based model offers enhanced accuracy and broader applicability in LCF analysis.
- This approach uniquely accounts for ratcheting strain damage, surpassing mean stress-based models.
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